A biosensor of this type was configured as follows in the past.
Specifically, there are provided a reagent and first and second electrodes that become conductive via this reagent when a biological sample is supplied to the reagent, and the reagent comprises a mediator, an oxidoreductase, and an adhesive agent.
That is, when a biological sample is supplied to the reagent, the biological sample and the oxidoreductase react, the mediator transmits the electrons produced by this reaction, and the redox current flowing between the first and second electrodes at this point is measured to find a blood glucose level.
The reagent (and particularly the mediator) is known to be affected by light (visible light) and to affect measurement accuracy. Therefore, there were attempts in the past to provide a light effect reducing agent to the walls of the holding container holding the biosensor (see Patent Literature 1, for example).